题目: 题目链接: 题解: 莫比乌斯反演 推导过程如下 ∑ i = 1 n ∑ j = 1 i F [ j ] [ g c d ( i , j ) = 1 ] \sum_{i=1}^{n}\sum_{j=1}^{i} {F[j][gcd(i,j)=1]} ∑i=1n∑j=1iF[j][gcd(i,j)=1] 可以转化为 ∑ i = 1 n F [ i ] ∑ j = i n g
C1-xor chall.py from flag import flagdef encrypt(x, y):key='zxb'result=''for i in range(len(x)):result+=chr(ord(x[i])^ord(y[i])^ord(key[i%3]))return resultx = flagy = flag[1:] + flag[0]enc = open(